Here are my reasons, not in any particular order:
1. It is a great way to de-stress and helps revive my energy. It's particularly pleasant to do this amidst hectic work schedule.
2. I am very opinionated, and blogging provides just the right platform to express whatever I want without tiring people out by talking.
3. You can reach out to a wider audience through a blog than Facebook or Twitter, and only those who are interested can read the post.
4. I like to write, but lack the focus and bandwidth to write a book. The ideal length of a blog post suits me just about perfectly to rant about all sorts of random things.
5. It's like photographs: will have memories associated with it. I think it would be interesting to look back and smile reading what I used to write when I was young.
Happy blogging folks!!